1. Field of the Invention
The present invention relates to a single-eye-type head mount display device (hereinafter referred to as HMD) for magnifying an image generated by an image display means to a magnified virtual image and enabling the magnified virtual image to be seen by either one of the eyes of the user.
2. Discussion of the Background
The necessity for observing a display image shown by the image display means simultaneously with a background image has resulted in the development of single-eye-type HMDs. Various applications of such single-eye-type HMDs to computer display devices and instruction display devices for the aid of manual operations have also been in demand.
A known example of such single-eye-type HMDs is disclosed in JAPANESE PATENT LAYING-OPEN GAZETTE No. H-2-63379. Another example disclosed in JAPANESE PATENT LAYING-OPEN GAZETTE No. H-3-189677 is known as a single-eye-see-through-type HMD.
The single-eye-see-through-type HMD described in JAPANESE PATENT LAYING-OPEN GAZETTE No. H-3-189677 combines an image beam emitted from an optical system arranged at the side of the face of the user with a light beam from a background by means of a combiner arranged in front of the face, thereby superposing a display image upon a background image. In this conventional single-eye-type HMD, the eye for observing the display image is fixed to either the left eye or the right eye, i.e., the user cannot select the eye for observing the display image.
Generally people have a preferential eye for observation among the two eyes. The degree of contribution of the preferential eye for observation of images depends upon the person. The preferential eye for observing the display image may vary depending upon the state of application of the HMD and the physical characteristics of the user. It is also possible that the user of the HMD may have a disorder in one eye. It is accordingly inconvenient to fix the eye for observing the display image in the single-eye-type HMD to either the left eye or the right eye.
An object of the present invention is thus to solve the above problem and provide a single-eye-type HMD that enables the user to observe a composite image of a background image and a display image and to readily select the eye for observing the display image.